1/*
2 * Opus decoder/demuxer common functions
3 * Copyright (c) 2012 Andrew D'Addesio
4 * Copyright (c) 2013-2014 Mozilla Corporation
5 *
6 * This file is part of FFmpeg.
7 *
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23#ifndef AVCODEC_OPUS_H
24#define AVCODEC_OPUS_H
25
26#include <stdint.h>
27
28#include "libavutil/audio_fifo.h"
29#include "libavutil/float_dsp.h"
30#include "libavutil/frame.h"
31
32#include "libswresample/swresample.h"
33
34#include "avcodec.h"
35#include "get_bits.h"
36
37#define MAX_FRAME_SIZE               1275
38#define MAX_FRAMES                   48
39#define MAX_PACKET_DUR               5760
40
41#define CELT_SHORT_BLOCKSIZE         120
42#define CELT_OVERLAP                 CELT_SHORT_BLOCKSIZE
43#define CELT_MAX_LOG_BLOCKS          3
44#define CELT_MAX_FRAME_SIZE          (CELT_SHORT_BLOCKSIZE * (1 << CELT_MAX_LOG_BLOCKS))
45#define CELT_MAX_BANDS               21
46#define CELT_VECTORS                 11
47#define CELT_ALLOC_STEPS             6
48#define CELT_FINE_OFFSET             21
49#define CELT_MAX_FINE_BITS           8
50#define CELT_NORM_SCALE              16384
51#define CELT_QTHETA_OFFSET           4
52#define CELT_QTHETA_OFFSET_TWOPHASE  16
53#define CELT_DEEMPH_COEFF            0.85000610f
54#define CELT_POSTFILTER_MINPERIOD    15
55#define CELT_ENERGY_SILENCE          (-28.0f)
56
57#define SILK_HISTORY                 322
58#define SILK_MAX_LPC                 16
59
60#define ROUND_MULL(a,b,s) (((MUL64(a, b) >> ((s) - 1)) + 1) >> 1)
61#define ROUND_MUL16(a,b)  ((MUL16(a, b) + 16384) >> 15)
62#define opus_ilog(i) (av_log2(i) + !!(i))
63
64enum OpusMode {
65    OPUS_MODE_SILK,
66    OPUS_MODE_HYBRID,
67    OPUS_MODE_CELT
68};
69
70enum OpusBandwidth {
71    OPUS_BANDWIDTH_NARROWBAND,
72    OPUS_BANDWIDTH_MEDIUMBAND,
73    OPUS_BANDWIDTH_WIDEBAND,
74    OPUS_BANDWIDTH_SUPERWIDEBAND,
75    OPUS_BANDWIDTH_FULLBAND
76};
77
78typedef struct RawBitsContext {
79    const uint8_t *position;
80    unsigned int bytes;
81    unsigned int cachelen;
82    unsigned int cacheval;
83} RawBitsContext;
84
85typedef struct OpusRangeCoder {
86    GetBitContext gb;
87    RawBitsContext rb;
88    unsigned int range;
89    unsigned int value;
90    unsigned int total_read_bits;
91} OpusRangeCoder;
92
93typedef struct SilkContext SilkContext;
94
95typedef struct CeltContext CeltContext;
96
97typedef struct OpusPacket {
98    int packet_size;                /**< packet size */
99    int data_size;                  /**< size of the useful data -- packet size - padding */
100    int code;                       /**< packet code: specifies the frame layout */
101    int stereo;                     /**< whether this packet is mono or stereo */
102    int vbr;                        /**< vbr flag */
103    int config;                     /**< configuration: tells the audio mode,
104                                     **                bandwidth, and frame duration */
105    int frame_count;                /**< frame count */
106    int frame_offset[MAX_FRAMES];   /**< frame offsets */
107    int frame_size[MAX_FRAMES];     /**< frame sizes */
108    int frame_duration;             /**< frame duration, in samples @ 48kHz */
109    enum OpusMode mode;             /**< mode */
110    enum OpusBandwidth bandwidth;   /**< bandwidth */
111} OpusPacket;
112
113typedef struct OpusStreamContext {
114    AVCodecContext *avctx;
115    int output_channels;
116
117    OpusRangeCoder rc;
118    OpusRangeCoder redundancy_rc;
119    SilkContext *silk;
120    CeltContext *celt;
121    AVFloatDSPContext *fdsp;
122
123    float silk_buf[2][960];
124    float *silk_output[2];
125    DECLARE_ALIGNED(32, float, celt_buf)[2][960];
126    float *celt_output[2];
127
128    float redundancy_buf[2][960];
129    float *redundancy_output[2];
130
131    /* data buffers for the final output data */
132    float *out[2];
133    int out_size;
134
135    float *out_dummy;
136    int    out_dummy_allocated_size;
137
138    SwrContext *swr;
139    AVAudioFifo *celt_delay;
140    int silk_samplerate;
141    /* number of samples we still want to get from the resampler */
142    int delayed_samples;
143
144    OpusPacket packet;
145
146    int redundancy_idx;
147} OpusStreamContext;
148
149// a mapping between an opus stream and an output channel
150typedef struct ChannelMap {
151    int stream_idx;
152    int channel_idx;
153
154    // when a single decoded channel is mapped to multiple output channels, we
155    // write to the first output directly and copy from it to the others
156    // this field is set to 1 for those copied output channels
157    int copy;
158    // this is the index of the output channel to copy from
159    int copy_idx;
160
161    // this channel is silent
162    int silence;
163} ChannelMap;
164
165typedef struct OpusContext {
166    OpusStreamContext *streams;
167    int             nb_streams;
168    int      nb_stereo_streams;
169
170    AVFloatDSPContext fdsp;
171    int16_t gain_i;
172    float   gain;
173
174    ChannelMap *channel_maps;
175} OpusContext;
176
177static av_always_inline void opus_rc_normalize(OpusRangeCoder *rc)
178{
179    while (rc->range <= 1<<23) {
180        rc->value = ((rc->value << 8) | (get_bits(&rc->gb, 8) ^ 0xFF)) & ((1u << 31) - 1);
181        rc->range          <<= 8;
182        rc->total_read_bits += 8;
183    }
184}
185
186static av_always_inline void opus_rc_update(OpusRangeCoder *rc, unsigned int scale,
187                                          unsigned int low, unsigned int high,
188                                          unsigned int total)
189{
190    rc->value -= scale * (total - high);
191    rc->range  = low ? scale * (high - low)
192                      : rc->range - scale * (total - high);
193    opus_rc_normalize(rc);
194}
195
196static av_always_inline unsigned int opus_rc_getsymbol(OpusRangeCoder *rc, const uint16_t *cdf)
197{
198    unsigned int k, scale, total, symbol, low, high;
199
200    total = *cdf++;
201
202    scale   = rc->range / total;
203    symbol = rc->value / scale + 1;
204    symbol = total - FFMIN(symbol, total);
205
206    for (k = 0; cdf[k] <= symbol; k++);
207    high = cdf[k];
208    low  = k ? cdf[k-1] : 0;
209
210    opus_rc_update(rc, scale, low, high, total);
211
212    return k;
213}
214
215static av_always_inline unsigned int opus_rc_p2model(OpusRangeCoder *rc, unsigned int bits)
216{
217    unsigned int k, scale;
218    scale = rc->range >> bits; // in this case, scale = symbol
219
220    if (rc->value >= scale) {
221        rc->value -= scale;
222        rc->range -= scale;
223        k = 0;
224    } else {
225        rc->range = scale;
226        k = 1;
227    }
228    opus_rc_normalize(rc);
229    return k;
230}
231
232/**
233 * CELT: estimate bits of entropy that have thus far been consumed for the
234 *       current CELT frame, to integer and fractional (1/8th bit) precision
235 */
236static av_always_inline unsigned int opus_rc_tell(const OpusRangeCoder *rc)
237{
238    return rc->total_read_bits - av_log2(rc->range) - 1;
239}
240
241static av_always_inline unsigned int opus_rc_tell_frac(const OpusRangeCoder *rc)
242{
243    unsigned int i, total_bits, rcbuffer, range;
244
245    total_bits = rc->total_read_bits << 3;
246    rcbuffer   = av_log2(rc->range) + 1;
247    range      = rc->range >> (rcbuffer-16);
248
249    for (i = 0; i < 3; i++) {
250        int bit;
251        range = range * range >> 15;
252        bit = range >> 16;
253        rcbuffer = rcbuffer << 1 | bit;
254        range >>= bit;
255    }
256
257    return total_bits - rcbuffer;
258}
259
260/**
261 * CELT: read 1-25 raw bits at the end of the frame, backwards byte-wise
262 */
263static av_always_inline unsigned int opus_getrawbits(OpusRangeCoder *rc, unsigned int count)
264{
265    unsigned int value = 0;
266
267    while (rc->rb.bytes && rc->rb.cachelen < count) {
268        rc->rb.cacheval |= *--rc->rb.position << rc->rb.cachelen;
269        rc->rb.cachelen += 8;
270        rc->rb.bytes--;
271    }
272
273    value = rc->rb.cacheval & ((1<<count)-1);
274    rc->rb.cacheval    >>= count;
275    rc->rb.cachelen     -= count;
276    rc->total_read_bits += count;
277
278    return value;
279}
280
281/**
282 * CELT: read a uniform distribution
283 */
284static av_always_inline unsigned int opus_rc_unimodel(OpusRangeCoder *rc, unsigned int size)
285{
286    unsigned int bits, k, scale, total;
287
288    bits  = opus_ilog(size - 1);
289    total = (bits > 8) ? ((size - 1) >> (bits - 8)) + 1 : size;
290
291    scale  = rc->range / total;
292    k      = rc->value / scale + 1;
293    k      = total - FFMIN(k, total);
294    opus_rc_update(rc, scale, k, k + 1, total);
295
296    if (bits > 8) {
297        k = k << (bits - 8) | opus_getrawbits(rc, bits - 8);
298        return FFMIN(k, size - 1);
299    } else
300        return k;
301}
302
303static av_always_inline int opus_rc_laplace(OpusRangeCoder *rc, unsigned int symbol, int decay)
304{
305    /* extends the range coder to model a Laplace distribution */
306    int value = 0;
307    unsigned int scale, low = 0, center;
308
309    scale  = rc->range >> 15;
310    center = rc->value / scale + 1;
311    center = (1 << 15) - FFMIN(center, 1 << 15);
312
313    if (center >= symbol) {
314        value++;
315        low = symbol;
316        symbol = 1 + ((32768 - 32 - symbol) * (16384-decay) >> 15);
317
318        while (symbol > 1 && center >= low + 2 * symbol) {
319            value++;
320            symbol *= 2;
321            low    += symbol;
322            symbol  = (((symbol - 2) * decay) >> 15) + 1;
323        }
324
325        if (symbol <= 1) {
326            int distance = (center - low) >> 1;
327            value += distance;
328            low   += 2 * distance;
329        }
330
331        if (center < low + symbol)
332            value *= -1;
333        else
334            low += symbol;
335    }
336
337    opus_rc_update(rc, scale, low, FFMIN(low + symbol, 32768), 32768);
338
339    return value;
340}
341
342static av_always_inline unsigned int opus_rc_stepmodel(OpusRangeCoder *rc, int k0)
343{
344    /* Use a probability of 3 up to itheta=8192 and then use 1 after */
345    unsigned int k, scale, symbol, total = (k0+1)*3 + k0;
346    scale  = rc->range / total;
347    symbol = rc->value / scale + 1;
348    symbol = total - FFMIN(symbol, total);
349
350    k = (symbol < (k0+1)*3) ? symbol/3 : symbol - (k0+1)*2;
351
352    opus_rc_update(rc, scale, (k <= k0) ? 3*(k+0) : (k-1-k0) + 3*(k0+1),
353                   (k <= k0) ? 3*(k+1) : (k-0-k0) + 3*(k0+1), total);
354    return k;
355}
356
357static av_always_inline unsigned int opus_rc_trimodel(OpusRangeCoder *rc, int qn)
358{
359    unsigned int k, scale, symbol, total, low, center;
360
361    total = ((qn>>1) + 1) * ((qn>>1) + 1);
362    scale   = rc->range / total;
363    center = rc->value / scale + 1;
364    center = total - FFMIN(center, total);
365
366    if (center < total >> 1) {
367        k      = (ff_sqrt(8 * center + 1) - 1) >> 1;
368        low    = k * (k + 1) >> 1;
369        symbol = k + 1;
370    } else {
371        k      = (2*(qn + 1) - ff_sqrt(8*(total - center - 1) + 1)) >> 1;
372        low    = total - ((qn + 1 - k) * (qn + 2 - k) >> 1);
373        symbol = qn + 1 - k;
374    }
375
376    opus_rc_update(rc, scale, low, low + symbol, total);
377
378    return k;
379}
380
381int ff_opus_parse_packet(OpusPacket *pkt, const uint8_t *buf, int buf_size,
382                         int self_delimited);
383
384int ff_opus_parse_extradata(AVCodecContext *avctx, OpusContext *s);
385
386int ff_silk_init(AVCodecContext *avctx, SilkContext **ps, int output_channels);
387void ff_silk_free(SilkContext **ps);
388void ff_silk_flush(SilkContext *s);
389
390/**
391 * Decode the LP layer of one Opus frame (which may correspond to several SILK
392 * frames).
393 */
394int ff_silk_decode_superframe(SilkContext *s, OpusRangeCoder *rc,
395                              float *output[2],
396                              enum OpusBandwidth bandwidth, int coded_channels,
397                              int duration_ms);
398
399int ff_celt_init(AVCodecContext *avctx, CeltContext **s, int output_channels);
400
401void ff_celt_free(CeltContext **s);
402
403void ff_celt_flush(CeltContext *s);
404
405int ff_celt_decode_frame(CeltContext *s, OpusRangeCoder *rc,
406                         float **output, int coded_channels, int frame_size,
407                         int startband,  int endband);
408
409extern const float ff_celt_window2[120];
410
411#endif /* AVCODEC_OPUS_H */
412